An optical communication network is known that is made up of N rings including first and second bidirectional optical rings each having at least two annular optical fibers. The optical communication network is provided with an optical communication network node apparatus that sets transmission paths of respective wavelengths making up wavelength multiplexed light including a plurality of wavelengths within each optical ring and between respective optical rings in the N rings. For example, this corresponds to the optical communication network described in Nonpatent Literature 1.
A technique has been proposed to constrain the scale of nodes performing the cross connect of the wavelength multiplexed light by performing routing (path setting) on the basis of a waveband (band) including a predetermined number of wavelengths in the optical communication network. For example, this corresponds to the technique described in Nonpatent Literature 2.    Nonpatent Literature 1: Sato, “Broadband Optical Networking Technology”, Institute of Electronics, Information and Communication Engineers, 2003    Nonpatent Literature 2: Kakehashi, Hasegawa, and Sato, IEICE Technical Report, PN2006-12, August 2006